Acoustic wave device and acoustic wave module including the same

ABSTRACT

An acoustic wave device includes a piezoelectric substrate, functional elements, an outer peripheral support layer, a cover portion, and a protective layer covering the cover portion. A hollow space is defined by the piezoelectric substrate, the outer peripheral support layer, and the cover portion, and the functional elements are disposed in the hollow space. The acoustic wave device further includes an under bump metal layer, a wiring pattern, and a through-electrode that connects these elements. In the protective layer, a through-hole to be filled with a conductor to electrically connect a solder ball and the under bump metal layer is provided. The outer peripheral support layer includes a protruding portion protruding to the hollow space. When the acoustic wave device is seen in plan view, at least a portion of the through-hole overlaps the hollow space, and an end portion of the protruding portion overlaps an inner region of the through-hole.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese PatentApplication No. 2017-166611 filed on Aug. 31, 2017 and is a ContinuationApplication of PCT Application No. PCT/JP2018/025823 filed on Jul. 9,2018. The entire contents of each application are hereby incorporatedherein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to an acoustic wave device and an acousticwave module including the acoustic wave device and, in particular, to apackage structure of an acoustic wave device.

2. Description of the Related Art

In electronic apparatuses such as mobile phones or smart phones,acoustic wave devices including surface acoustic wave (SAW) resonatorsor bulk acoustic wave (BAW) resonators are used. In recent years,electronic apparatuses have been reduced in size and thickness, andaccordingly reduction in size and height of acoustic wave devices hasbeen required. To achieve this, a wafer level package (WLP) structure,which uses the chip itself of an acoustic wave device as a package, hasbeen proposed.

An acoustic wave device having a general WLP structure has aconfiguration such that a plurality of functional elements are disposedon a piezoelectric substrate in a hollow space that is formed by thepiezoelectric substrate, an outer peripheral support layer disposedaround a surface of the piezoelectric substrate, and a cover portionprovided on the outer peripheral support layer. In a case of a surfaceacoustic wave (SAW) device, an interdigital transducer (IDT) is disposedas a functional element.

In an acoustic wave device, when the dimension of the outer peripheralsupport layer in the width direction is increased, the proportion of anarea that the outer peripheral support layer occupies on the mainsurface of the piezoelectric substrate increases. Therefore, the spacefor disposing functional elements such as an IDT electrode is reduced,and the degree of freedom in design decreases. In order to achievefurther reduction in size of an acoustic wave device, it is desirable toincrease the proportion of an area (hollow space) in which functionalelements such as an IDT electrode can be disposed on the piezoelectricsubstrate. In order to enlarge the hollow space, it is necessary toreduce the proportion of the outer peripheral support layer on thepiezoelectric substrate. In this case, however, it is also necessary toprevent a decrease in rigidity against an external pressure.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide an increase to anarea in which functional elements can be disposed in an acoustic wavedevice while maintaining sufficient rigidity and resistance against anexternal pressure.

An acoustic wave device according to a preferred embodiment of thepresent invention includes a piezoelectric substrate, a plurality offunctional elements that are provided on the piezoelectric substrate, anouter peripheral support layer, a cover portion, and a protective layerthat covers the cover portion. The outer peripheral support layer isdisposed on the piezoelectric substrate around a region in which theplurality of functional elements are provided. The cover portion facesthe piezoelectric substrate with the outer peripheral support layerinterposed therebetween. A hollow space is defined by the piezoelectricsubstrate, the outer peripheral support layer, and the cover portion,and the plurality of functional elements are disposed in the hollowspace. The acoustic wave device further includes first and secondconductive portions and a wiring pattern. The first conductive portionis provided between the cover portion and the protective layer. Thewiring pattern is disposed on the piezoelectric substrate and iselectrically connected to at least one of the plurality of functionalelements. The second conductive portion connects the first conductiveportion and the wiring pattern to each other. In the protective layer, athrough-hole that is to be filled with a conductor to electricallyconnect a connection terminal provided outside the acoustic wave deviceand the first conductive portion to each other is provided. The outerperipheral support layer includes a protruding portion that protrudestoward the hollow space. When the acoustic wave device is seen in planview, at least a portion of the through-hole overlaps the hollow spaceand an end portion of the protruding portion overlaps an inner region ofthe through-hole.

An acoustic wave device according to a preferred embodiment of thepresent invention includes a piezoelectric substrate, a plurality offunctional elements that are provided on the piezoelectric substrate, anouter peripheral support layer, a cover portion, a protective layer thatcovers the cover portion, and an inner support layer. The outerperipheral support layer is disposed on the piezoelectric substratearound a region in which the plurality of functional elements areprovided. The cover portion faces the piezoelectric substrate with theouter peripheral support layer interposed therebetween. A hollow spaceis defined by the piezoelectric substrate, the outer peripheral supportlayer, and the cover portion, and the plurality of functional elementsare disposed in the hollow space. The acoustic wave device furtherincludes first and second conductive portions and a wiring pattern. Thefirst conductive portion is provided between the cover portion and theprotective layer. The wiring pattern is disposed on the piezoelectricsubstrate and is electrically connected to at least one of the pluralityof functional elements. The second conductive portion connects the firstconductive portion and the wiring pattern. In the protective layer, athrough-hole that is to be filled with a conductor to electricallyconnect a connection terminal provided outside the acoustic wave deviceand the first conductive portion to each other is provided. The internalsupport layer is disposed in the hollow space and supports the coverportion. When the acoustic wave device is seen in plan view, at least aportion of the through-hole overlaps the hollow space, and an endportion of the internal support layer overlaps an inner region of thethrough-hole.

An acoustic wave device according to a preferred embodiment of thepresent invention includes a piezoelectric substrate, a functionalelement disposed on the piezoelectric substrate, an outer peripheralsupport layer, a cover portion, a protective layer, a wiring electrode,first to third conductive portions, and an internal support layer. Theouter peripheral support layer is disposed on the piezoelectricsubstrate and surrounds a region in which the functional element isprovided when the acoustic wave device is seen in plan view. The coverportion is supported by the outer peripheral support layer and isdisposed above the functional element. The protective layer is disposedon the cover portion and a through-hole is provided in a portion of theprotective layer. The wiring electrode is disposed on the piezoelectricsubstrate and is connected to the functional element. The firstconductive portion is disposed between the cover portion and theprotective layer. The second conductive portion is connected to thewiring electrode and the first conductive portion. At least a portion ofthe third conductive portion is disposed in the through-hole, and thethird conductive portion is connected to the first conductive portion.The internal support layer is disposed between the cover portion and thepiezoelectric substrate in a region that is surrounded by the outerperipheral support layer when the acoustic wave device is seen in planview. At least a portion of the internal support layer overlaps thethrough-hole when the acoustic wave device is seen in plan view.

With preferred embodiments of the present invention, it is possible toincrease an area in which functional elements can be disposed in anacoustic wave device while maintaining sufficient rigidity against anexternal pressure.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an acoustic wave module in which anacoustic wave device according to a first preferred embodiment of thepresent invention is provided.

FIG. 2 is a first view illustrating a force applied from a mountsubstrate to the acoustic wave device in a mounting process.

FIG. 3 is a second view illustrating a force applied from a mountsubstrate to the acoustic wave device in a mounting process.

FIG. 4 illustrates an example of an arrangement of protruding portionsof an outer peripheral support layer when the acoustic wave device ofFIG. 1 is seen in plan view.

FIG. 5 illustrates another example of an arrangement of protrudingportions of an outer peripheral support layer when the acoustic wavedevice of FIG. 1 is seen in plan view.

FIG. 6 illustrates another example of an arrangement of protrudingportions of an outer peripheral support layer when the acoustic wavedevice of FIG. 1 is seen in plan view.

FIGS. 7A to 7C illustrate configurations of a through-hole provided in aprotective layer.

FIG. 8 is a cross-sectional view of an acoustic wave module in which anacoustic wave device according to a second preferred embodiment of thepresent invention is provided.

FIG. 9 illustrates a first example of an arrangement of an outerperipheral support layer and an internal support layer when the acousticwave device of FIG. 8 is seen in plan view.

FIG. 10 illustrates a second example of an arrangement of an outerperipheral support layer and an internal support layer when the acousticwave device of FIG. 8 is seen in plan view.

FIG. 11 illustrates a third example of an arrangement of an outerperipheral support layer and an internal support layer when the acousticwave device of FIG. 8 is seen in plan view.

FIG. 12 illustrates a fourth example of an arrangement of an outerperipheral support layer and an internal support layer when the acousticwave device of FIG. 8 is seen in plan view.

FIG. 13 is a cross-sectional view of an acoustic wave module in which anacoustic wave device according to a third preferred embodiment of thepresent invention is provided.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereafter, preferred embodiments of the present invention will bedescribed in detail with reference to the drawings. In the drawings,elements that are the same as or similar to each other will be denotedby the same reference numerals and descriptions of such elements willnot be repeated.

First Preferred Embodiment

FIG. 1 is a cross-sectional view of an acoustic wave module 100 in whichan acoustic wave device 110 according to a first preferred embodiment ofthe present invention is provided on a mount substrate 50. As an exampleof an acoustic wave device according to the present preferredembodiment, a surface acoustic wave device that includes an IDTelectrode as a functional element will be described. However, anacoustic wave device may be a device that uses a bulk acoustic wave.

Referring to FIG. 1 , the acoustic wave device 110 includes apiezoelectric substrate 10, an outer peripheral support layer 20, acover portion 30, a protective layer 40, functional elements 60, andconnection terminals 70.

The piezoelectric substrate 10 is preferably made of a piezoelectricsingle crystal material, such as, for example, lithium tantalate(LiTaO₃), lithium niobate (LiNbO₃), alumina, silicon (Si), or sapphire;or a piezoelectric multi-layer material composed of LiTaO₃ or LiNbO₃.The plurality of functional elements 60 are disposed on thepiezoelectric substrate 10. The functional elements 60 include a pair ofIDT electrodes made of an electrode material that is preferably, forexample, an elemental metal that is at least one of aluminum, copper,silver, gold, titanium, tungsten, platinum, chrome, nickel, andmolybdenum; an alloy including one of these metals as a main component;or the like. A surface acoustic wave resonator is defined by thepiezoelectric substrate 10 and the IDT electrodes.

The outer peripheral support layer 20, which is preferably made of, forexample, a resin, is provided on an outer peripheral portion of the mainsurface of the piezoelectric substrate 10. By disposing thepiezoelectric substrate 10 and the cover portion 30 so as to face eachother with the outer peripheral support layer 20 therebetween, a hollowspace is defined around the plurality of functional elements 60including the IDT electrodes. Thus, a surface acoustic wave propagatesin a portion of the piezoelectric substrate 10 adjacent to the hollowspace.

A surface of the cover portion 30 on a side opposite from the hollowspace is covered by the protective layer 40 preferably made of, forexample, an insulating resin such as an epoxy resin. An under bump metallayer 66 is provided between the cover portion 30 and the protectivelayer. Through-holes 80 are provided in the protective layer 40. Each ofthe through-holes 80 is located at a position where at least a portionthereof overlaps the hollow space when the acoustic wave device 110 isseen in plan view.

A wiring pattern 62 to electrically connect the functional elements 60to each other is provided on the main surface of the piezoelectricsubstrate 10. The wiring pattern 62 is electrically connected to theunder bump metal layer 66 via through-electrodes (vias) 64 that extendthrough the outer peripheral support layer 20 and the cover portion 30.The under bump metal layer 66 extends from connection portions with thethrough-electrodes 64 in the inward direction of the acoustic wavedevice 110, and is connected to the connection terminals 70 viaconductors 68 with which the through-holes 80 provided in the protectivelayer 40 are filled. The connection terminals 70 are electricallyconnected to a wiring pattern 52 on the mount substrate 50.

In the acoustic wave device 110 according to the first preferredembodiment, protruding portions 22, which are portions of the outerperipheral support layer 20 that protrude toward the hollow space, areprovided. The protruding portions 22 are disposed such that end portionsthereof overlap the through-holes 80 when the acoustic wave device 110is seen in plan view. As described below, the protruding portions 22 areconfigured to receive a stress that is applied via the connectionterminals 70 from the outside in the process of mounting the acousticwave device 110 onto the mount substrate 50, and thus deformation of thecover portion 30 is reduced or prevented.

Here, a stress that is applied to the acoustic wave device 110 via theconnection terminals 70 will be described. In the process of mountingthe acoustic wave device 110 on the mount substrate 50 (reflow process),in general, the acoustic wave device 110 is brought into close contactwith the mount substrate 50 on which solder balls (the connectionterminals 70) have been disposed beforehand, the acoustic wave device110 and the mount substrate 50 in this state are conveyed into ahigh-temperature furnace to melt the solder, and then the acoustic wavedevice 110 and the mount substrate 50 are connected to each other bycooling these.

At this time, the solder balls are disposed on the mount substrate 50 soas to protrude from the mount substrate 50, and the protruding portions(projecting portions) of the solder balls contact the acoustic wavedevice 110 when the acoustic wave device 110 is brought into closecontact with the mount substrate 50. A solder ball generally includes ametal filler, the metal filler presses the acoustic wave device 110, andthus a pressure is locally applied to the acoustic wave device 110.

Even in a case where each of the through-holes 80 of the protectivelayer 40 is not filled with a conductor and the projecting portion ofthe solder ball can be contained in the through-hole 80 when theacoustic wave device 110 is brought into close contact with the mountsubstrate 50, if displacement occurs between the projecting portion andthe through-hole 80 as illustrated in FIG. 2 or if the dimension of theprojecting portion is larger than the dimension of the through-hole 80as illustrated in FIG. 3 , a pressure is locally applied to an edgeportion of the through-hole 80.

In a case where the dimension of the outer peripheral support layer 20in the width direction is reduced in order to widen the hollow space, ifa pressure is locally applied by the projecting portion of the solderball as described above, the cover portion 30 may deform and thedeformed cover portion 30 may make contact with the functional elements60, and the contact may lead to undesirable characteristics or breakage.

Moreover, due to a moment generated by deformation of the cover portion30 and a local pressure, a stress may be applied also to a connectionportion between the through-electrode 64 and the under bump metal layer66, and the stress may lead to loose connection or breakage.

In the first preferred embodiment, protruding portions are provided inportions of the outer peripheral support layer 20, and end portions ofthe protruding portions are located in regions of the through-holes 80.Because the protruding portions of the outer peripheral support layer 20can support a stress that is generated by a pressure that is locallyapplied, deformation of the cover portion 30 can be reduced orprevented.

FIGS. 4 to 6 each illustrate an example of an arrangement of theprotruding portions of the outer peripheral support layer 20 when theacoustic wave device 110 of FIG. 1 is seen in plan view. In each ofFIGS. 4 to 6 , the acoustic wave device 110 has a rectangular orsubstantially rectangular shape in plan view. However, the planar shapeof the acoustic wave device 110 is not limited to this. The planar shapeof the acoustic wave device 110 may be a circle, an ellipse, or anotherpolygon, for example. In each of FIGS. 4 to 6 and FIGS. 9 to 12described below, to facilitate understanding, the cover portion 30 istransparently illustrated and the positions of the through-holes 80 areshown by broken lines.

In FIG. 4 , the protruding portions 22 are provided at the four cornersof the rectangular or substantially rectangular outer peripheral supportlayer 20. In the configuration shown in FIG. 4 , each of the protrudingportions 22 receives a portion of a stress in the transversal direction(the X-axis direction in the figure) and the longitudinal direction (theY-axis direction). By reducing the dimension in the width direction ofportions of the outer peripheral support layer 20 in which theprotruding portions 22 are not provided (the dimension in the Y-axisdirection for the short sides, and the dimension in the X-axis directionfor the long sides), an area occupied by the hollow space is increased.Although an example in which the protruding portions 22 have rectangularor substantially rectangular shapes is illustrated in FIG. 4 , theshapes of the protruding portions are not limited to rectangular shapes,and may be curved as in the case of protruding portions 22D shown inFIG. 5 .

The protruding portions need not be located at the four corners as inFIGS. 4 and 5 , and may be located in any appropriate way as long as theprotruding portions can support a stress that is generated. FIG. 6illustrates an example of configuration in which protruding portions 22Aand 22B are disposed at portions of respective sides of a rectangular orsubstantially rectangular outer peripheral support layer 20.

In FIG. 6 , the protruding portions 22A, which are provided at the longsides, support a stress in the X-axis direction, and the protrudingportions 22B, which are provided at the short sides, support a stress inthe Y-axis direction. Although an example in which one protrudingportion is provided on each side is illustrated in FIG. 6 , a pluralityof protruding portions may be provided on each side. However, when thenumber of protruding portions is increased, although an allowable stressincreases, a region in which functional elements can be disposed becomeslimited, because an area occupied by the support layer in the hollowspace increases. Therefore, preferably, the number of protrudingportions is determined in accordance with the magnitude of an estimatedstress and an allowable stress for each protruding portion.

Also with the structure illustrated in FIG. 6 , the protruding portions22A and 22B can respectively receive an X-axis-direction component and aY-axis-direction component of a load applied to the acoustic wave device110 from the outside, and the widths of portions of the outer peripheralsupport layer 20 in which the protruding portions 22A and 22B are notprovided can be reduced. Therefore, the hollow space for the functionalelements 60 can be enlarged while maintaining the rigidity of theacoustic wave device 110 against an external pressure.

In the configuration described above with reference to FIG. 1 , asillustrated in FIG. 7A, the entire or substantially the entirethrough-hole 80 of the protective layer 40 is filled with the conductor68, and a solder ball that is the connection terminal 70 is connected tothe conductor 68. However, as illustrated in FIG. 7C, the through-hole80 need not be filled with a conductor at all, or as illustrated in FIG.7B, the through-hole 80 may be filled with a conductor 68B to the heightof a portion of the through-hole 80. In other words, the height of asurface 68X of each of the conductors 68 and 68B in the through-holes 80in the Z-axis direction (the thickness direction of the acoustic wavedevice 110) may the same or substantially the same as the height of asurface 40X of the protective layer 40 in the Z-axis direction, or aportion of the surface 68X may be lower than the height of the surface40X of the protective layer 40. In the cases illustrated in FIGS. 7B and7C, vacant portions of the through-holes 80 are to be respectivelyfilled with melted solder 70B and melted solder 70C.

Also in a case where the planar shape of the acoustic wave device is notrectangular, by providing the protruding portions of the outerperipheral support layer so as to receive a stress component in a firstdirection (for example, the X-axis direction) and a stress component ina second direction perpendicular to the first direction (for example,the Y-axis direction) when the acoustic wave device is seen in planview, advantages similar to those described above are obtained.

Second Preferred Embodiment

In each of the configurations described above in the first preferredembodiment, the protruding portions, which are provided in the outerperipheral support layer 20, receive a stress.

In each of configurations described below in a second preferredembodiment of the present invention, in addition to the outer peripheralsupport layer, an internal support layer is disposed in the hollowspace, and the internal support layer receives a partial stresscomponent.

FIG. 8 is a cross-sectional view of an acoustic wave module 100A inwhich an acoustic wave device 110A according to the second preferredembodiment is provided. In the cross section illustrated in FIG. 8 ,although a protruding portion is not provided in the outer peripheralsupport layer 20, an internal support layer 25 is provided in the hollowspace. The internal support layer 25 is disposed such that an endportion thereof overlaps a region of a through-hole 80 when the acousticwave device 110A is seen in plan view. The internal support layer 25 canreceive a stress in the horizontal direction in FIG. 8 .

FIG. 9 illustrates an example of an arrangement of the outer peripheralsupport layer 20 and internal support layers 25 when the acoustic wavedevice 110A of FIG. 8 is seen in plan view. In FIG. 9 , the internalsupport layers 25 provide the function of the protruding portions 22A toreceive a stress in the X-axis direction in the plan view of FIG. 6shown in the first preferred embodiment. Regarding a stress in theY-axis direction, protruding portions 22B provided at the short sides ofthe outer peripheral support layer 20 receive the stress in the same orsimilar way as in FIG. 6 .

The internal support layers 25 may receive a stress in the Y-axisdirection, instead of a stress in the X-axis direction. Alternatively,the internal support layers 25 may receive both of a stress in theX-axis direction and a stress in the Y-axis direction. As illustrated inFIG. 9 , a through-electrode 27 may be provided in an internal supportlayer 25.

In the configuration illustrated in FIG. 9 , the internal support layers25 are provided to receive a stress. However, for example, in aconfiguration in which an internal support layer is provided for anotherpurpose, a protruding portion may be provided in the internal supportlayer, and a portion of the protruding portion may overlap athrough-hole when the acoustic wave device is seen in plan view. In FIG.9 , end portions of the protruding portions 22B overlap thethrough-holes 80.

FIG. 10 illustrates an exemplary configuration in which an internalsupport layer 25A extends in the hollow space in the Y-axis direction inFIG. 10 and in which protruding portions 26A to receive a stress in theX-axis direction are provided. FIG. 11 illustrates an example of a casewhere columnar internal support layers 25B are provided in the hollowspace. In this case, protruding portions 26B to receive a stress in theX-axis direction from the columnar internal support layers 25B areprovided. FIG. 12 illustrates an example in which protruding portions26C extend to an outer peripheral support layer from an internal supportlayer 25C, which extends in the Y-axis direction in FIG. 11 , andportions of the protruding portions 26C overlap through-holes 80. Theprotruding portions 26A to 26C are each a portion of an internal supportlayer.

Also with the configurations illustrated in FIGS. 10 to 12 , it ispossible to set the hollow space to be wide while maintaining rigiditybecause the protruding portions of the internal support layer receive astress in a predetermined direction. Also in FIGS. 10 to 12 , theprotruding portions of the internal support layer may receive a stressin the Y-axis direction, instead of or in addition to a stress in theX-axis direction.

Third Preferred Embodiment

In the configurations described above in the first preferred embodimentand the second preferred embodiment, the through-electrodes 64, whichare provided in the outer peripheral support layer 20, connect the underbump metal layer 66, which is provided between the cover portion 30 andthe protective layer 40, and the wiring pattern 62 on the piezoelectricsubstrate 10 to each other. In a configuration described below in athird preferred embodiment of the present invention, conductors thatconnect the under bump metal layer 66 and the wiring pattern 62 to eachother are provided on side surfaces of the outer peripheral supportlayer 20 and the cover portion 30.

FIG. 13 is a cross-sectional view of an acoustic wave module 100B inwhich an acoustic wave device 110B according to the third preferredembodiment is provided.

Referring to FIG. 13 , the under bump metal layer 66 and the wiringpattern 62 are connected to each other via side wiring conductors 64Bthat are provided on an outer peripheral side surface of the outerperipheral support layer 20. Moreover, a protective layer 40B covers notonly the cover portion 30 but also the entire or substantially theentire outer peripheral side surface of the outer peripheral supportlayer 20. That is, the side wiring conductors 64B are provided betweenthe outer peripheral support layer 20 and the protective layer 40B.Descriptions of elements other than those described above, which arecommon to those shown in FIG. 1 , will not be repeated.

Also in the acoustic wave device 110B illustrated in FIG. 13 ,protruding portions 22 are provided in the outer peripheral supportlayer 20, and end portions of the protruding portions 22 are disposed soas to overlap the through-holes 80. Accordingly, also with the thirdpreferred embodiment, as with the first preferred embodiment, it ispossible to enlarge the hollow space for the functional elements 60while maintaining the rigidity of the acoustic wave device 110B againstan external pressure.

Although not illustrated in the figures, also with the configuration ofthe third preferred embodiment, which includes the side wiringconductors 64B, the internal support layer (and protruding portionsthereof) may receive a stress, as in the second preferred embodiment.

As heretofore described, according to the present preferred embodiment,an acoustic wave device having a WLP structure has the followingconfiguration: a protruding portion that partially protrudes from anouter peripheral support layer and/or an internal support layer and anend portion of a protruding portion that protrudes from the internalsupport layer are/is disposed so as to overlap a region of athrough-hole when the acoustic wave device is seen in plan view, and thedimension of the outer peripheral support layer in the width directionis reduced. Thus, it is possible to reduce the proportion of an areaoccupied by the outer peripheral support layer in the acoustic wavedevice, while receiving a stress due to an external pressure with theprotruding portion. Accordingly, it is possible to enlarge a hollowspace for functional elements while maintaining the rigidity andresistance of the acoustic wave device against an external pressure.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

1: An acoustic wave device comprising: a piezoelectric substrate; aninterdigital transducer (IDT) electrode on the piezoelectric substrate;an outer peripheral support layer on the piezoelectric substrate andsurrounding a region in which the IDT electrode is provided when theacoustic wave device is seen in plan view from a thickness direction ofthe piezoelectric substrate; a cover portion supported by the outerperipheral support layer and disposed above the IDT electrode; aprotective layer on the cover portion and including a portion in which athrough-hole is provided; a wiring electrode on the piezoelectricsubstrate and connected to the IDT electrode; a first conductive portionbetween the cover portion and the protective layer; a second conductiveportion connected to the wiring electrode and the first conductiveportion; a third conductive portion at least a portion of which isdisposed in the through-hole and is connected to the first conductiveportion; and an internal support layer between the cover portion and thepiezoelectric substrate in a region that is surrounded by the outerperipheral support layer when the acoustic wave device is seen in planview from the thickness direction of the piezoelectric substrate;wherein the internal support layer includes a first portion extending ina first direction and a second portion extending in a second directiondifferent from the first direction; and at least a portion of theinternal support layer overlaps the through-hole when the acoustic wavedevice is seen in plan view from the thickness direction of thepiezoelectric substrate. 2: The acoustic wave device according to claim1, wherein a dimension of the first portion of the internal supportlayer in the first direction is greater than a dimension of the secondportion of the internal support layer in the second direction; and atleast a portion of the second portion of the internal support layeroverlaps the through-hole when the acoustic wave device is seen in theplan view. 3: The acoustic wave device according to claim 2, wherein thesecond portion of the internal support layer includes a plurality ofsecond portions extending in the second direction; the through-holeincludes a plurality of through-holes; and each of the plurality ofsecond portions of the internal support layer overlaps one of theplurality of through-holes respectively when the acoustic wave device isseen in the plan view. 4: The acoustic wave device according to claim 3,wherein the first portion of the internal support layer is connectedbetween each of the plurality of second portions of the internal supportlayer. 5: The acoustic wave device according to claim 3, wherein theacoustic wave device has a rectangular or substantially rectangularshape including a shorter side and a longer side when the acoustic wavedevice is seen in the plan view; and the second direction is parallel orsubstantially parallel to the shorter side of the acoustic wave device.6: The acoustic wave device according to claim 4, wherein the acousticwave device has a rectangular or substantially rectangular shapeincluding a shorter side and a longer side when the acoustic wave deviceis seen in the plan view; and the second direction is parallel orsubstantially parallel to the shorter side of the acoustic wave device.7: The acoustic wave device according to claim 2, wherein the firstportion of the internal support layer is connected to the second portionof the internal support layer. 8: The acoustic wave device according toclaim 7, wherein the acoustic wave device has a rectangular orsubstantially rectangular shape including a shorter side and a longerside when the acoustic wave device is seen in the plan view; and thesecond direction is parallel or substantially parallel to the shorterside of the acoustic wave device. 9: The acoustic wave device accordingto claim 2, wherein the first direction is perpendicular orsubstantially perpendicular to the second direction. 10: The acousticwave device according to claim 2, wherein the through-hole has arectangular or substantially rectangular shape when the acoustic wavedevice is seen in the plan view. 11: The acoustic wave device accordingto claim 1, wherein the through hole includes a first through-hole andsecond through-hole; the second portion of the internal support layerincludes a plurality of second portions each extending in the seconddirection different from the first direction; one of the plurality ofsecond portions and another one of the plurality of second portions ofthe internal support layer are on opposite sides of the first portion ofthe internal support layer when the acoustic wave device is seen in theplan view; and at least a portion of the one of the plurality of secondportions of the internal support layer overlaps the first through-holeand at least a portion of the another one of the plurality of secondportions of the internal support layer overlaps the second through-holewhen the acoustic wave device is seen in the plan view. 12: The acousticwave device according to claim 11, wherein a dimension of the firstportion of the internal support layer in the first direction is greaterthan a dimension of the one of the plurality of second portions of theinternal support layer in the second direction. 13: The acoustic wavedevice according to claim 11, wherein a dimension of the first portionof the internal support layer in the first direction is greater thaneach of a dimension of the one of the plurality of second portions ofthe internal support layer in the second direction and a dimension ofthe another one of the plurality of second portions of the internalsupport layer in the second direction. 14: The acoustic wave deviceaccording to claim 11, wherein the first portion of the internal supportlayer is connected to each of the one of the plurality of secondportions and the another one of the plurality of second portions of theinternal support layer. 15: The acoustic wave device according to claim11, wherein the first direction is perpendicular or substantiallyperpendicular to the second direction. 16: The acoustic wave deviceaccording to claim 11, wherein each of the first through-hole and thesecond through-hole has a rectangular or substantially rectangular shapewhen the acoustic wave device is seen in the plan view. 17: The acousticwave device according to claim 1, wherein the acoustic wave device has arectangular or substantially rectangular shape including a shorter sideand a longer side when the acoustic wave device is seen in the planview; the first direction is parallel or substantially parallel to thelonger side of the acoustic wave device and the second direction isparallel or substantially parallel to the shorter side of the acousticwave device; and at least a portion of the second portion of theinternal support layer overlaps the through-hole when the acoustic wavedevice is seen in the plan view. 18: The acoustic wave device accordingto claim 17, wherein a dimension of the first portion of the internalsupport layer in the first direction is greater than a dimension of thesecond portion of the internal support layer in the second direction.19: The acoustic wave device according to claim 17, wherein the firstportion of the internal support layer is connected to the second portionof the internal support layer. 20: The acoustic wave device according toclaim 17, wherein the through-hole has a rectangular or substantiallyrectangular shape when the acoustic wave device is seen in the planview.